In this type of system, it is tried to suppress the collision of wireless communication. For example, in Patent Literature 1, the following technology is proposed. If there is a wireless network including a plurality of wireless stations that use the same channel, then, signals transmitted from wireless stations that belong to another wireless network are detected, and a collision avoidance time is determined on the basis of the detected signals. This reduces a collision probability of the signals transmitted from the wireless stations.
Alternatively, in Patent Literature 2, the following technology is proposed. If there are two or more data packets in a transmission buffer, then, a random number value used for backoff control upon transmission of a second data packet is generated upon transmission of a first data packet, and the random number value is written in the first data packet. An ACK packet for the first data packet is received from a wires base station, and a random number value written in the ACK packet is read and used for the backoff upon transmission of the second data packet. This reduces a collision probability of the data packets transmitted from wireless terminals.
Alternatively in Patent Literature 3, the following technology is proposed. If the avoidance of the collision of wireless packets is realized by a method such as carrier sense multiple access/collision avoidance (CSMA/CA), a use status of a common channel is collected, and it is determined whether or not there is much free time on the common channel after passing a predetermined time. A maximum value of the collision avoidance time is changed or held. This improves a transmission efficiency of a communication system.
Alternatively in Patent Literature 4, the following technology is proposed. When a wireless base station apparatus or a wireless terminal apparatus transmits data packets, the apparatus firstly transmits a packet having no data upon acquisition of a transmission right after performing carrier sense for a fixed period or for a random period, and after completion of the transmission of the packet, the apparatus continuously transmits data packets at short intervals without performing the carrier sense.